The present invention relates generally to semiconductor chip packages and, more particularly, to structures for shielding semiconductor chip packages with enhanced mechanical reliability.
Stacked Multichip Modules (MCM""s), Chip Scale Packages (CSP""s) and Micro Ball Grid Arrays (xcexcBGA""s) are electronic packages that increase the density of packaged silicon by forming a package having a volume only slightly greater than the bare silicon active device. Such packages often employ the stacking of silicon dies or die/interposer structures into a single package for surface mounting on a printed circuit board (PCB). MCM""s, CSP""s and xcexcBGA""s are formed with silicon dies wirebonded to an organic interposer. The interposer is further connected to the PCB assembly through solder balls. Organic encapsulation is dispensed or molded over the die to provide mechanical and environmental protection for the die/interposer structure.
A conventional MCM, CSP or xcexcBGA package is generally not significantly shielded against EMI/RFI. Shielding, when it is used, typically consists of placing a MCM, CSP or xcexcBGA package within a metal outer shell structure. This method of shielding adds considerable volume, weight and complexity to the overall package structure.
Implementations consistent with the present invention provide a shielding structure for a circuitry package, such as a MCM, CSP or xcexcBGA package, through application of a coating of a metal filled polymer to surface areas of the circuitry package. Additionally, implementations consistent with the present invention may include the placement of an electrically conductive particle filled polymer gasket between the circuitry package and a conductive trace of the PCB. Implementations consistent with the present invention, thus, provide a structure for shielding a circuitry package against EMI/RFI that may enhance the mechanical integrity of the interconnection between the circuitry package and the PCB.
In accordance with the purpose of the invention as embodied and broadly described herein, a circuit shielding structure includes a circuitry package, and a layer of conductive polymer material coating at least a portion of the circuitry package.
In another implementation consistent with the present invention, a structure for interconnecting a circuitry package with a circuit board includes a conductive trace applied to the circuit board, an electrically conductive particle filled polymer gasket, and a circuitry package adhered to the electrically conductive particle filled polymer gasket, wherein the gasket is soldered to the conductive trace such that solder wicks through the gasket to a surface of the circuitry package.
In a further implementation consistent with the present invention, a method of shielding a circuitry package includes applying a layer of conductive polymer material to at least a portion of the circuitry package.
In an additional implementation consistent with the present invention, a method of interconnecting a circuitry package with a circuit board includes applying a conductive trace to the circuit board, adhering the circuitry package to an electrically conductive particle filled polymer gasket, applying solder to the conductive trace, and applying heat to the solder such that the solder wicks from the conductive trace, through the gasket, to a surface of the circuitry package.